A device-to-device (D2D) communications technology has been introduced in a Long Term Evolution (LTE) system. D2D is a direct device-to-device communications technology. A largest difference between the D2D and a conventional cellular communications technology lies in that communication can be directly performed between user equipments (UE) without a need of forwarding by a base station (e.g. Evolved NodeB (eNodeB)). The base station may perform resource configuration, scheduling, and coordination, and the like, to assist the user equipments in the direct communication. A typical application scenario of D2D communication is a public safety scenario such as communication between firemen, and a typical service type is a voice service.
As shown in FIG. 1, a D2D communications system includes a base station 101, user equipment (UE) 1, and UE2. The base station 101 and the UE1 may perform wireless cellular communication, and the UE1 and the UE2 may perform D2D communication.
As intelligent driving and self-driving technologies emerge for vehicles, people are stimulated to study use of an existing cellular communications network to assist in vehicle-to-vehicle communication. An LTE system has advantages such as a high rate, a low delay, large coverage, and the like, supports high-speed mobile terminals, and is applicable to the vehicle-to-vehicle communication.
To sum up, in a wireless communications system such as the LTE system, a technology applicable to the vehicle-to-vehicle (V2V) communication is in an urgent need.